Erosion is one of the scourges of Champagne viticulture, often combatted by the spreading of fresh, decay-resistant bark (mulch) in thick layers between the vines. But though natural and environmentally-friendly, this technique is not enough to keep pace with progress. Hence Ayala’s decision to test the use of cover-cropping: the sowing of grass between rows of vines.

Vineyard manager Frédéric Husson picks his words with care. "Grass is very effective against erosion, on condition that you rule out everything except meadow grass". Researchers selected meadow grass for its perennial growth habit and resistance to trampling and uprooting. Its roots penetrate deep into into the soil, clinging to soil particles and holding the soil in place.

The suitability of cover-cropping does however depend on the vine plot in question. Grass needs plenty of depth and a rich supply of organic matter. As our expert points out: "Meadow grass traps nitrates, reduces the quantity of nitrogen and phosphorus in the petioles and lowers the incidence of grey mould".

The grass is planted between the rows in a 50cm band, covering half the width of the inter-row and achieving a 50% reduction in herbicide use. Then there is the effect of cover-cropping on vine vigour. Over the course of 3-4 years, meadow grass reduces vegetative growth by around one third, and vine productivity by as much as 20% compared with a traditional vine, dropping to 10% thereafter.

Spring frosts can happen much more frequently with this type of technique and the vine can be more vulnerable to dry periods because the grass consumes a lot of water. But this is a price worth paying, it seems, to get musts with a slightly raised alcohol content (at most between 0.2 and 0.5 of alcohol by volume). Also, due to a lower level of nitrogen, fermentation takes longer than is customary. Secondary fermentation is also more difficult, maybe due to the resulting elevations in residual sugar.

Specific equipment

Légende: In 2004, ecological principles guided the lyre-training of vines in the Moët vineyard

The weeding of the vines and the cutting of the grass are delicate tasks that require special equipment because tractors are liable to slip. At Ayala, where trials have been underway for more than 10 years, Alain Ducellier and Jean-Claude Boissel prefer to continue testing before reaching a conclusion: "while it may now be thought possible to understand the effect of this technique on the vine, our oenologists have had only three years to examine its effects on the quality of the wine. It will be another 10-15 years before we are in a position to present a preliminary assessment".

Mumm "plays" the lyre

Vineyard director Olivier Brun points out the climate variations across the Champagne region: "1972 and 1984 were bad years for us, whereas 1985 and 1990 are still remembered for their excellent harvests even though the winter of 1985 recorded drops in temperature worthy of the Antarctic, down to -31.5C in places."

Légende: Mumm tests lyre-training

Mumm teste les vignes en lyre

For the sake of consistent quality year on year, Mumm is examining new training systems and experimenting with lyre-trainIng: two canes are trained to grow upwards (rather than dangling down). This style of vine training was pioneered by the Bordeaux INRA, and seems to offer an ideal combination of quality and productivity. The researchers point to the importance of the plant’s vegetative growth (when sugar accumulates in the leaves) for the subsequent maturation phase (when sugar accumulates in the berries). Having more leaf, these vines transport more sugar and more acids to the berries. To say nothing of old vines that have more wood and therefore more reserves. Like the ant in the fable by La Fontaine, old vines accumulate carbohydrate reserves and store them from one year to the next. According to the rules, the combined distance between the rows and the vines in each row cannot exceed 2.5m. Lyre-trained vines, on the other hand, require an inter-row spacing of 3.3m and an inter-vine spacing of 1.1m. The INAO therefore made an exception to the rules and three 50-are plots of lyre-trained vines were respectively planted to the Chardonnay (Avize), the Pinot Noir (Ambonnay) and the Pinot Meunier (Savigny).

The buds escape the frost"In 1988 we sought permission to plant bigger plots, to see how the vine would perform from the moment of planting and to make the vineyards more homogeneous in terms of work and wine-making." This led to the planting of three further plots, this time measuring 80 ares each, one of Chardonnay in Cramant, another of Pinot Noir in Verzenay and a third of Pinot Meunier in Marzilly. The results were mixed. "We didn’t regularly get the yield expected for the appellation, particularly not for the Pinot Noir and Pinot Meunier. But the buds did escape the spring frosts thanks to their position further away from the ground.

Given the standing of our AOC, it’s essential to have a certain number of buds per hectare — not easy with such a low planting density (a third of the density of conventional vines). We’re not yet there in terms of crop control (vine productivity and cluster weight) but we do at least know that lyre-training optimizes sunlight exposure. It also yields musts with more acidity, which makes for crisper wines. The experience has certainly been a useful starting point for thinking about alternative training methods.

The decision must eventually rest with man, using evolving technology and questioning the positive and negative effects of lyre-training on the quality of the wine. Scientific and technical understanding helps us to understand the choices of our forebears. After that, it is up to us to make our own choices, subject of course to the quality that we aim to deliver to our consumers." For the House of Mumm, born and bred in Champagne, what counts above all is improving quality.

At Moët & Chandon, every slope is important

The law of 1927 defined the precise limits of the AOC areas under vine at the time, which included vineyards with a 30-40% slope. As heir to some of these hillside holdings, Moët & Chandon was keen to optimize performance and introduced terrace-planting in 1990.

Thanks to their steep slopes, these vineyards already enjoyed excellent exposure to sunlight, with a very porous, chalky subsoil that favoured water absorption and the retention of moisture. All that remained was to shape the slopes in line with their natural contours — use terracing to maintain and enhance the natural values of the landscape. Mechanical diggers gradually sculpted the hillsides into grand flights of terraces that today rise up the slopes like giant steps. Each one has a maximum width of 1.6m, planted with perfectly straight rows of vines that blend with their surroundings. In summer, the vines and banks are completely camouflaged by an abundance of green foliage. From 1990 to 1993, two hectares were planted in Sainte-Hélène, in the commune of Hautvillers; 50 ares in the commune of Moussy; and 10 hectares in the Valley of the Marne. "The biggest drawback, admits François LHotte, is the planting of the vineyard itself. There’s a greater area of ground exposed to the sun, and it dries out faster.

Légende: Moët & Chandon terraces shaped by their environment

Les terrasses de Moët & Chandon s’adaptent à l’environnement

The banks of the terraces (and usually the sides too) are planted with grasses, the vine roots drawing their water from the ground already dried by cover-cropping. It takes four years for the roots of grasses and vines to become established and capable of stabilizing the soil." Yields achieve a satisfactory level after six years, which is two or three years more than for a traditional vine. This is due to the lower planting density: 3,000-4,000 plants per hectare, which is roughly half the density of a conventional vineyard. The INAO has granted an exception in this case, authorizing a lower planting density while maintaining a workable distance of 90cm between vines. It’s hard to see how you could make this distance any smaller.

"For the sake of normal to near-normal yields the vines have to be planted sufficiently close together. It’s a compromise between the minimum distance required for pruning (to maintain healthy fruit-bearing wood) and an ideal production target of 10-12,000kg/ha" says François Lhotte. Vineyard maintenance therefore calls for a particularly light touch. "With an aisle width of just 1.1m, we need specialised equipment — conventional row-straddling machines are out of the question.
Despite a certain instability, articulated tractors were the only viable choice.
We have also had to develop special tools for thinning and organise ourselves differently for a harvest that must always done by hand." The vines are sprayed with basic treatments from the air, by helicopter. Happily, terraced vines, being naturally well ventilated, need less treatments than conventional vineyards — ambient humidity is also much lower, reducing the incidence of bunch rot ahead of the harvest.

High operating costs"The cost of such an undertaking is higher by around 30%," says François Lhotte. "But the knowledge gained in the process certainly justifies the outlay. After around 10 years, the yield from a terraced vineyard is about 70% that of a conventional vineyard — as evidenced by our most recent vintage, which produced 10,000 kilos of grapes. We are in any case happy to serve as a testing ground for Champagne as a whole."